As English speakers, we might be wondering why “I have forgotten,” in the caption above, isn’t using the first person (yo or "I") conjugation of haber, as in [yo] he olvidado...

In fact, Cienfue could have sung precisely that, which would be the most “English-like” way of expressing his thought:

[yo] he olvidado quién soy yoI have forgotten who I am

Another alternative would be the pronominal (think “reflexive”) form, olvidarse:

[yo] me he olvidado de quién soy yoI have forgotten who I am

Note that the pronominal option requires a “de” after olvidado. The reason for this is that olvidarse, like most pronominal verbs, does not take a direct object, while olvidar is “transitive”—meaning it does (and must) take a direct object. Native speakers often just “know” this instinctively.

Cienfue doesn’t opt for either of these, rather going with what, to English speakers, will be the most “foreign” (though commonplace in Spanish) construction, olvidársele. Olvidársele is what is known as the "impersonal" (or “terciopersonal,” third person) construction of olvidarse.

In contrast to what we are accustomed to in English, the subject of the sentence is the thing forgotten, while the person doing the forgetting is expressed as an indirect object (signified by the le appended to olvidarse). Something "gets forgotten" (passive voice) "by someone."

So, when Cienfue sings,

Se me ha olvidado quién soy yo

the subject of the sentence is “quién soy yo” (who I am) and the indirect object is “me” (me).

Cienfue is most literally saying:“ ‘Who I am’ has been forgotten by me”

Most Spanish speakers, even if pressed, will find precious little (if any) difference in meaning amongst the three possible constructions. There are definitely regional as well as personal preferences.

It can also be argued that there are nuanced differences in emphasis. For example, the “impersonal” form places the least “blame” on the person doing the forgetting. This type of verb construction has even been called sin culpa (without blame), and it’s not the first time we’ve encountered it

in our discussions.

What if you want to simply say “I forgot.”? (e.g. in response to Por qué no fuiste a trabajar? Why didn’t you go to work?)